Reserach On Design Technology Of High-efficiency Boost DC-DC Power Management Chip

Due to the rapid development of science and technology,electronic products have become very critical daily-use items in people’s lives,such as mobile phones and laptops.In the update iteration of electronic products,display screens are getting larger and larger and require higher resolution,which requires a higher voltage to provide power to the screen,and the lithium battery provides a DC voltage of about 3.7V,which is not enough to drive the display screen to work normally.Therefore,a power management chip is needed to convert the voltage provided by the lithium battery into a higher and more stable voltage for use in electronic products.The performance of the power management chip determines to a large extent the use time and lifespan of electronic products.Through the analysis of Boost DC-DC,this paper studies and designs a high-efficiency Boost DC-DC switching power converter,which uses PWM peak current mode control.According to the different characteristics of the control loop,different optimized compensation schemes are designed:the voltage loop uses an RC compensation network for frequency compensation,and the current loop uses slope compensation to improve system stability.The introduction of slope compensation in the current loop will limit the load capacity of the system.This article proposes a solution to this problem.In the specific implementation of the chip,a constant current source is used to charge and discharge the capacitor to generate a segmented ramp signal with high linearity.Analyze the source of converter loss and optimize them separately to achieve efficiency improvement.Aiming at the problem of chip damage caused by excessive current in the system startup phase,the soft start of the chip is researched and designed by using the digital signal to control the positive input of the error amplifier;for the problem that the freewheeling tube inherent in the Boost converter structure cannot be completely shut down.Using the series PMOS and the body diode of the freewheeling tube to form an inverse series structure,realizing the true shutdown of the freewheeling tube;in view of the various options of the system on the output voltage,the external single-wire interface is used to count and encode the output voltage to achieve the flexible configuration of output voltage value.Based on the CSMC 0.18μm BCD process model,this paper designs the circuit and system in Cadence software,and performs Spectre simulation verification on the overall circuit,and finally achieves physical verification through the back-end layout design.The results show that,when L=10μH,CIN=10μF,COUT=22μF,f=1.45MHz,the output voltage can reach 5.8V～7.9V with a typical value of 7.6 V in the input voltage range of 2.9V-4.5 V.The conversion efficiency of the system can reach 91.6%and the output voltage ripple is 1mV when the load current is 0～55mA.The load regulation rate is 0.5mV/mA and the linear regulation rate is 0.01 V/V,which provides an effective design solution for a high-efficiency Boost DC-DC convertor.